lav2mpeg: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/lav2mpeg - from package: mjpegtools

You may install the required package with command apt-get install {package}
Error in other languages:
lav2mpeg: bevel nie gevind nie
lav2mpeg: comandă negăsită
lav2mpeg: comando não encontrado
lav2mpeg: commande introuvable
lav2mpeg: command not found
lav2mpeg: käsku ei ole
lav2mpeg: không tìm thấy lệnh
lav2mpeg: komanda nerasta
lav2mpeg: Kommando nicht gefunden.
lav2mpeg: kommandot finns inte
lav2mpeg: komut yok
lav2mpeg: nie znaleziono polecenia
lav2mpeg: níor aimsíodh an t-ordú
lav2mpeg: no se encontró la orden
lav2mpeg: no s'ha trobat l'ordre
lav2mpeg: opdracht niet gevonden
lav2mpeg: parancs nem található
lav2mpeg: perintah tidak ditemukan
lav2mpeg: príkaz nenájdený
lav2mpeg: příkaz nenalezen
lav2mpeg: команда не найдена
lav2mpeg: командата не е открита
lav2mpeg: 命令找不到
lav2mpeg: コマンドが見つかりません